Militant Islamists seized more territory in northern Iraq on Wednesday, moving south toward Baghdad as government forces scrambled to regroup after losing control of the country’s second-largest city.

Fighters linked to the Islamic State of Iraq and Syria, an Al Qaeda splinter group also battling the government in neighboring Syria, swept through the city of Tikrit in Salahuddin province and strengthened their grip in northern Iraq.

The clashes in Tikrit came a day after the militants seized control in Mosul following a four-hour battle with U.S.-trained government forces. Iraqi troops and police officers reportedly abandoned much of their hardware, shed their uniforms and fled the city as fighters took over the Nineveh provincial government building and burned down police and army headquarters.

The fighting raised international concerns as the militants appeared in position to seize a large swath of oil-rich territory across northern Iraq to the border with Syria. The conflict reflected one of the fundamental divisions in Iraq in the wake of the withdrawal of U.S. troops in late 2011: marginalized Sunni Muslims, who are a minority in the country but a majority in some areas of the north, striking back at a weak Shiite Muslim-led central government and its security forces.

Activists who favor the ISIS reported that the group’s fighters ransacked Mosul's central bank, seizing $420 million, and took the Turkish Consulate, where they detained 48 people, including the head of the diplomatic mission. Turkish state media confirmed the takeover.

The assault led to a mass exodus of residents from the city, according to the International Organization for Migration, with an estimated 500,000 people making their way eastward to the nearby Kurdish-controlled regions of Iraq. Kurdish authorities moved to restrict entry only to those who "have family already residing in the Kurdish region or a sponsor."

Other residents, however, seemed to welcome the takeover, describing the fighters as "revolutionaries" and urging residents to clean up the streets, open shops and remove the concrete barriers that had been a part of the city's landscape for six years. Atheel Nujayfi, the Mosul-born Sunni governor of Nineveh province, said power had been restored.

Agence France-Presse / Getty Images

A picture taken with a mobile phone shows Iraqi soldiers talking as smoke billows behind them on a road in Hawijah, west of Kirkuk, in northern Iraq on June 11.

A picture taken with a mobile phone shows Iraqi soldiers talking as smoke billows behind them on a road in Hawijah, west of Kirkuk, in northern Iraq on June 11. (Agence France-Presse / Getty Images)

Prime Minister Nouri Maliki, a day after calling on parliament to declare a state of emergency and for residents to join local militias to "combat terrorism," appeared visibly perturbed at a news conference Wednesday, insisting that the insurgent forces were "not of the level that could face and confront the forces of the army and police."

"The army and police and the security organizations are much stronger than they [ISIS] are, but there was a trick and a conspiracy," he said. "We will deal with it, but after we end their presence."

His pledge to recapture the province was dismissed by Nujayfi, who demanded at a news conference that military leaders be put on trial.

"We are united in rejecting the granting of Maliki additional powers through a state of emergency," the Nineveh governor posted on his personal Facebook page. "Can any reasonable person give the failed security apparatus more powers for another chance?"

The army is widely viewed by Iraq's Sunni population as carrying out sectarian attacks at the behest of Maliki's Shiite-dominated government.

"So long as there is lack of genuine reconciliation and integration in Iraq, crises of confidence will fester, leaving weak institutions prone to unraveling," said Ramzy Mardini, nonresident fellow at the Atlantic Council in Amman, Jordan. “The divisions are so deep that during times of crisis, the first instinct is to gain an advantage against rivals rather than seek to compromise for the collective good."

ISIS, whose precursor, the Islamic State of Iraq, had spearheaded the insurgency against U.S. forces following the 2003 invasion of Iraq, was created in the wake up of the anti-government uprisings against Syrian President Bashar Assad. The group's growing influence in Syria led to a wide-scale rout by rival factions that restricted its presence to the eastern province of Deyr Al-Zor and Raqqa.

The group’s advances in Iraq appear to further its vision for an Islamic "caliphate" that rejects the borders between Iraq and Syria. ISIS supporters flooded social media with images of soldiers destroying fences and checkpoints between the two countries with bulldozers.

They also posted images of Humvees and helicopters that had been left behind by the retreating Iraqi forces — equipment provided by the U.S. government to defeat the insurgents who have now commandeered them.

"So far 40 Humvees have been delivered to ISIS in Raqqah," declared Shaam o'file, a pro-ISIS activist, on his Twitter feed.

One image purported to show Abu Omar Shishani, an ISIS commander from Chechnya who operates in the Islamist-dominated regions in northern Syria, climbing out of a Humvee, while others depicted grinning fighters atop armored vehicles.

The Syrian Foreign Ministry released a statement Wednesday saying that Iraq was experiencing terrorist actions "in the framework of a global conspiracy against the Iraqi and Syrian people, through the terrorist invasion that targets its unity and the destruction of its people and infrastructure."

"The Syrian Arab Republic condemns these terrorist actions and expresses its support and solidarity to the government, army and the brother Iraqi people," the statement said.